Abstract

The vasodilatory response to passive leg movement (PLM) appears to provide a novel, non-invasive assessment of vascular function. However, PLM has yet to be compared to the established non-invasive assessment of vascular health, flow mediated dilation (FMD). Therefore, as an initial evaluation of the construct validity of PLM, upright seated and supine PLM as well as brachial (BA) and superficial femoral (SFA) artery FMDs were performed in 10 young (22±1) and 30 old (73±2) subjects. During upright seated PLM, the peak change in leg blood flow (∆LBF) and leg vascular conductance (∆LVC) were significantly correlated with BA (r=0.57 and r=0.66) and SFA (r=0.44 and r=0.41, ∆LBF and ∆LVC, respectively) FMD. Further, although the relationships were not as strong, the supine PLM response was also significantly correlated with BA (r=0.38 and r=0.35) and SFA (r=0.39 and r=0.35, ∆LBF and ∆LVC, respectively) FMD. Examination of the young and old separately, however, revealed that significant relationships persisted in both groups only for the upright seated PLM response and BA FMD (young: r=0.73 and r=0.77; old: r=0.35 and r=0.45, ∆LBF and ∆LVC, respectively). Normalizing FMD for shear rate during PLM abrogated all significant relationships between the PLM and FMD response, suggesting a role for nitric oxide (NO) in these associations. Collectively, these data indicate that PLM, particularly upright seated PLM, likely provides an index of vascular health analogous to the traditional FMD test. Given the relative ease of PLM implementation, these data have important positive implications for PLM as a clinical vascular health assessment.